Currently, carbonaceous materials are used as anode materials for lithium secondary cells. However, it is necessary to use an anode material with a higher capacity in order to further improve the capacity of a lithium secondary cell.
For the purpose of satisfying such demands, metals capable of forming alloys electrochemically with lithium, for example Si, Al, etc., which have a higher charge/discharge capacity, may be considered for use as anode materials. However, such metal-based anode materials undergo extreme changes in volume, as lithium intercalation/deintercalation progresses, and thus the active materials are finely divided and the lithium cells have poor cycle life characteristics.
Japanese Patent Application Laid-Open No. 2001-297757 discloses an anode material essentially comprising an α-phase (e.g. Si) consisting of at least one element capable of lithium intercalation/deintercalation and a β-phase that is an intermetallic compound or solid solution of the element with another element (b).
However, the anode material according to the prior art cannot provide sufficient and acceptable cycle life characteristics, and thus it may not be used as a practical anode material for a lithium secondary cell.